1. Field of the Invention
The present invention relates to a travel control apparatus that recognizes lane markings on the road from images recorded by a camera, and carries out travel control such that the vehicle travels along these lane markings.
2. Description of the Related Art
In the conventional vehicle steering apparatus disclosed, for example, in Japanese Unexamined Patent Application, First Publication, No. Hei 11-78948, is known in which lines on the road (for example, lane markings such as white lines) are detected by processing images obtained from a camera mounted on the vehicle that records the travel path, and compensates the steering torque input by the driver so that the vehicle travels along this line.
However, in the vehicle steering apparatus according to the conventional technology described above, in the case that the detection of the lines on the road is impossible, the execution of the steering control that compensates the steering torque input by the driver is suspended, and inappropriate steering control is prevented by restarting the steering control at a point in time when the detection of the line on the road can be detected.
However, the frequency that the detection of lines on the road becomes impossible due to the state of the surface of the road being traveled, or the state of the road surface, for example, accumulated snow, a bad surface, a wet surface, or the road surface in a tunnel or the like is high, and there are cases in which the steering control is switched on and off frequently. Thereby, the compensation of the steering torque input by the driver switches ON and OFF frequently, and there is a concern that this may cause discomfort for the driver.
In consideration of the above described problems, it is an object of the present invention to provide a travel control apparatus for a vehicle that carries out appropriate travel control so that the vehicle travels along recognized lane markings, and at the same time can prevent making the driver feel discomfort while travel control is being carried out.
In order to solve the problems described above and attain the object, in a first aspect of the vehicle travel control apparatus according to the present invention that comprises a travel path recognizing device (for example, the camera 25 and the image recognition processing unit 26 in the embodiments described below) that recognizes the travel path of the vehicle, a recognition condition determining device (for example, step S 01, step S 04, and step S 07 in the embodiments described below) that determines the quality of the recognition condition of the travel path recognizing device, and a travel control device (for example, step S 10 in the embodiments described below) that determines the possibility of executing the travel control for the vehicle using the results of the recognition of said travel path recognizing device based on the results of the determination of the recognition condition determining device, wherein said travel control device determines the possibility of executing the travel control for the vehicle based on at least one of the favorably determined continuous condition or the unfavorably determined continuous condition that is determined by the recognition condition determining device.
According to a vehicle travel control apparatus having the structure described above, the travel path recognition device analyses image data or the like of the travel path obtained by video recording using, for example, cameras mounted on the vehicle, and recognizes the lane markings, such as the white lines, on the travel path. At this time, the recognition condition determining device determines the quality of, for example, the recognition condition of the sequence of recognition processing and recognition results in the travel path recognizing device, for example, the possibility of recognition or the precision of the recognition results. In addition, the possibility of executing the travel control depends not simply on the results of the determination of the quality of the recognition condition determining device, but also on each continuing condition of the quality determination, such as the history of each continuous time interval.
Thereby, for example, even in the case that the quality determination in the recognition condition determining device switches frequently, it is possible to prevent the accompanying possibility of execution of the travel control from switching frequently, and the recognition condition determining device appropriately sets the possibility of execution of the travel control such that it is appropriately switched depending on each continuation condition of a favorable determination or unfavorable determination, and thereby it is possible to prevent the driver from feeling discomfort.
In a second aspect of the vehicle travel control apparatus according to the present invention, said continuous condition of the quality determination by the recognition condition determining device is the continuous time interval from the starting time of the favorable determination or unfavorable determination (for example, the count value of the ON time measuring counter TON and the count value of the OFF time measuring counter TOFF in the employments described below), and said travel control device determines the possibility of execution of the travel control of the vehicle based on a reference time (for example, the delay time TD in the embodiments described below) that is increased or decreased depending on the continuous time interval.
According to the vehicle travel control apparatus having the structure described above, for example, the longer the continuous time interval of the favorable determination, the travel control device determines that there exists a state appropriate for executing the travel control using the result of the recognition of the travel path recognizing device, and the reference time, for example the delay time when the possibility of execution of the travel control is switched, is decreased. In contrast, for example, the longer the continuous time interval of the unfavorable determination, the travel control device determines that there exists a state that is not appropriate for executing the travel control using the result of the recognition of the travel path recognizing device, and a reference time, for example, the delay time when the possibility of execution of the travel control is switched, is increased.
Thereby, the travel control device can determine the possibility of executing travel control by suitably determining whether or not it is in a state appropriate for executing the travel control using the result of the recognition of the travel path recognizing device based on the reference time, and thereby it is possible to prevent making the driver feel discomfort while travel control is being executed.
Furthermore, a third aspect of the vehicle travel control apparatus according to the present invention comprises a reference time update device (for example, step S 02 and step S 05 in the embodiments described below) that decreases said reference time in the case that there is a favorable determination by the recognition condition determining device and increases said reference time in the case that there is an unfavorable determination by the recognition condition determining device, and said travel control device compares the reference time with the favorable determination continuous time interval (for example, the count value of the ON time measuring counter TON in the embodiments described below) that is the continuous time interval from the start time of the favorable determination by said recognition condition determination device, and when the favorable determination continuous time interval is longer than said reference value, the execution of the travel control of the vehicle is permitted.
According to the vehicle travel control apparatus having the structure described above, during the switching of the possibility of execution of the travel control, for example, from the state in which the execution of the travel control is not permitted, when switching to the state in which execution is permitted, in the state in which execution of the travel control is not permitted, the reference time update device measured the continuous time interval of the unfavorable determination by the recognition condition determining device, and then increases the reference time, for example the delay time when switching the possibility of execution of the travel control, according to the continuous time interval of this unfavorable determination.
In addition, when there is a favorable determination by the recognition condition determining device, the travel control device compares the favorable determination continuous time interval, which is the continuous time interval from the start time of this favorable determination, with the reference time, and in the case that the favorable determination continuous time interval continues long enough to exceed the reference value, the execution of the travel control is permitted. Therefore, in the case that the favorable determination continuous time interval does not satisfy the reference time, the execution of the travel control is not permitted, and the state in which it is not permitted continues.
Thereby, for example, in the case that the favorable determination in the recognition condition determining device switches frequently, the travel control device determines that a state that is appropriate for executing travel control using the result of the recognition of the travel path recognition device does not exist, and frequent switching of the possibility of execution of the travel control can be prevented, and thereby it is possible to prevent making the driver feel discomfort while the travel control is being carried out.
Furthermore, in a fourth aspect of the vehicle travel control apparatus according to the present invention, it is possible to change at least one of either the ratio of the decrease (for example, the delay time shortening gain GR in the embodiments described below) when decreasing the reference time in the case that there is a favorable determination by said recognition condition determining device or the ratio of the increase (for example, the delay time extending gain GE in the embodiments described below) when increasing the reference time in the case that there is an unfavorable determination by said recognition condition determining device.
According to the vehicle travel control apparatus having the structure described above, the possibility of execution of the travel control can be switched even more appropriately for example, by allowing updating depending on the ratio of the increase or the ratio of the decrease of the reference time in addition to each continuous time interval of the quality determination when updating the reference value that serves as the delay time or the like when switching the possibility of execution of the travel control.
Furthermore, a fifth aspect of the vehicle control apparatus according to the present invention comprises an actuator (for example, the motor 20 in the embodiments described below) that drives a steering mechanism (for example, the manual steering power generating mechanism 16 in the embodiments described below) that can steer the front steering wheels (for example, the front steering wheels 19, 19 in the embodiments described below) of the vehicle, and a drive control device (for example, the EPS control apparatus 24 in the embodiments described below) that drives the actuator such that the vehicle travels along said travel path that has been recognized by the travel path recognizing device, wherein said drive control device updates the compensation proportion when compensating the steering torque based on the result of the determination of said recognition condition determining device.
According to a vehicle travel control apparatus having the structure described above, the travel control device determines the possibility of execution of the travel control according to each of the continuation conditions of the quality determination of the recognition condition determining device, and at the same time, updates the amount of the compensation of the steering torque during travel control depending on the result of the quality determination by the recognition condition determining device.
Thereby, the switching timing of the possibility of execution of the travel control can be appropriately set, and at the same time, the compensation proportion of the steering torque can be set to an appropriate value, and it is possible to prevent even further making the driver feel discomfort during travel control.
Furthermore, in a sixth aspect of the vehicle travel control apparatus according to the present invention, the larger the continuous proportion of the favorable determination by the recognition condition determining device, the more said drive control device increases the compensation proportion.
According to the vehicle travel control apparatus having the structure described above, the larger the continuation proportion of the favorable determination by the recognition condition determining device, i.e., the longer the continuous time interval of the favorable determination, the drive control device determines that there is a state suitable for executing the travel control using the result of the recognition of the travel path recognition device, and the compensation proportion of the steering torque during execution of the travel control is increased.
Thereby, during the condition suitable to executing the travel control, the steering of the driver is appropriately assisted during travel on a high-speed highway during clear or rainy weather or the like.
Furthermore, a seventh aspect of the vehicle travel control apparatus of the present invention comprises a deviation determining device (for example, the LKAS control apparatus 23 in the embodiments described below) that recognizes the position of the vehicle in the traverse direction of the travel path based on the result of the recognition of said travel path recognizing device, and when the position of this vehicle arrives at a predetermined reference position (for example, the deviation warning start threshold value TH1 in the embodiments described below) that indicates the deviation from the travel path, determines whether or not there is the possibility that the vehicle will deviate from the travel path, wherein the deviation determining device updates said reference position based on the result of the determination of the recognition condition determining device.
According to the vehicle travel control apparatus having the structure described above, in the case that the position of the vehicle with respect to the lane markings on the travel path recognized by the travel path recognition device departs from the predetermined reference position by a certain amount, the deviation determining device determines that there is the possibility that the vehicle will deviate from the travel path. At this time, the deviation determining device updates the reference position based on the result of the quality determination of the recognition condition determining device, and by making the recognition condition of the sequence of recognition processing and the result of the recognition or the like in the travel path recognizing device reflect the setting of the reference position, it is possible to carry out suitable deviation determination that depends on whether or not there exists a condition requiring caution during travel.
Furthermore, in an eighth aspect of the vehicle travel control device according to the present invention, the smaller the continuous proportion of the favorable determination by said recognition condition determining device, the deviation determining device updates said reference position such that, the possibility that the vehicle will deviate from the travel path is easily determined.
In a vehicle travel control apparatus having the structure described above, the smaller the continuous proportion of the quality determination by the recognition condition determining device the deviation determining device determines that there exists a condition requiring caution during travel, and the reference position is updated so that it is easy to determine that the possibility that the vehicle will deviate is high.
For example, the smaller the continuous proportion of the favorable determination, the easier it becomes to determine that the possibility the vehicle will deviate is high due to the reference position approaching the lane marking on the travel path. Depending on the results of this determination, it becomes possible to notify the driver about the necessity of caution during travel at a more suitable timing.
Furthermore, a ninth aspect of the vehicle travel control apparatus according to the present invention comprises a torque detection device (for example, the torque sensor 22 in the embodiments described below) that detects the steering torque input by the driver, a driving attention determining device (for example, a role also played by the LKAS control apparatus 23 in the embodiments described below) that determines the presence or absence of a decrease in the driving attention of the driver by comparing the condition of the change in the steering torque and a predetermined reference value (for example, the driver attention determining threshold value TH2 in the embodiments described below), wherein said driver attention determining device updates the reference value based on the result of the determination of said recognition condition determining device.
According to a vehicle travel control apparatus having the structure described above, in the case, for example, that the condition of the change of the steering torque input by the driver is smaller than a predetermined reference value, the driver attention determining device determines that the driver attention is decreasing. At this time, the driver attention determining device updates the reference value based on the result of the quality determination of the recognition condition determining device, and by making recognition condition of the sequence of recognition processing in the travel path recognizing device and the result of the recognition reflect the setting of the reference value, it is possible to carry out suitable driver attention determination depending on whether there is a condition requiring caution during travel.
Furthermore, in a tenth aspect of the vehicle travel control apparatus according to the present invention, the smaller the continuous proportion of the favorable determination by the recognition condition determining device, said driver attention determining device updates the reference value so that it is easy to determine that said driver attention is decreasing.
According to the vehicle travel control apparatus having the structure described above, the smaller the continuous proportion of the quality determination by the recognition condition determining device, the driver attention determining device determines that there exists a condition requiring caution during travel, and updates the reference value so that it is easy to determine that the driver attention is decreasing. Thereby, it is possible to notify the driver that caution during travel is required at a more suitable timing.